Amides

Perhaps the best known of all synthetic amides is the fiber known as nylon. In 1931, the American chemist Wallace Hume Carothers discovered a process for making one of the first synthetic fibers. He found that the addition of adipic acid to hexamethylene diamine resulted in the formation of a strong, fiber-like product to which he gave the name Nylon 66. The 66 part of the name reflects the fact that adipic acid and hexamethylene diamine each contain six carbon atoms in their molecules.

The reaction between these two substances results in the formation of a long polymer, somewhat similar to the structure of natural protein. As in protein, the subunits of nylon are joined by amide bonds. For this reason, both protein and nylon can be thought of as polyamides, compounds in which a large number of amide units are joined to each other in a long chain.

Other types of nylon were also developed at later dates. One form, known as Nylon 6, is produced by the polymerization of a single kind of molecule, 6-aminohexanoic acid. The bonding between sub-units in Nylon-6-amide bonds is the same as it is in Nylon 66. In all types of nylon, the fiber obtains its strength from hydrogen bonding that occurs between oxygen and hydrogen atoms on adjacent chains of the material.

Another type of polymer is formed when two of the simplest organic compounds, urea and formaldehyde, react with each other. In this reaction, amide bonds form between alternate urea and formaldehyde molecules, resulting in a very long polyamide chain. Urea formaldehyde polymers are in great demand by industry, where they are used as molding compounds, in the treatment of paper and textiles, and as a binder in particle board, to mention but a few uses.

An amide with which many people are familiar is acetaminophen, an analgesic (pain-killer). It is the active ingredient in products such as Amadil, Cetadol, Datril, Naprinol, Panadol, and Tylenol. Another amide analgesic is phenacetin, found in products such as APC (aspirin, phenacetin, and caffeine) tablets and Empirin.

Other commercially important amides include the insect repellant N,N-dimethyl-m-toluamide (Off, Deet), the local anesthetics lidocaine (Xylocaine) and dibucaine (Nupercaine), the tranquilizer meprobromate (Miltown, Equaine), and the insecticides Sevin and Mipcin.